Approximate hash verification of unused blockchain output

ABSTRACT

An example operation may include one or more of receiving a location of an output stored on a data structure of a blockchain, where the location comprises a path of hashes generated by a reduced-step hash instead of a full-step hash of the blockchain, performing an approximate hash verification on the path of hashes based on the reduced-step hash values to verify whether the output is unused, and in response to a determination that the output is unused as a result of the approximate hash verification, approving a use of the output by a client associated with the output.

TECHNICAL FIELD

This application generally relates to processes of a blockchain, andmore particularly, to a blockchain which integrates an approximate hashverification and thereby reduces the amount of computation needed forverification within a blockchain network.

BACKGROUND

A centralized database stores and maintains data in a single database(e.g., a database server) at one location. This location is often acentral computer, for example, a desktop central processing unit (CPU),a server CPU, or a mainframe computer. Information stored on acentralized database is typically accessible from multiple differentpoints. Multiple users or client workstations can work simultaneously onthe centralized database, for example, based on a client/serverconfiguration. A centralized database is easy to manage, maintain, andcontrol, especially for purposes of security because of its singlelocation. Within a centralized database, data redundancy is minimized asa single storing place of all data also implies that a given set of dataonly has one primary record.

However, a centralized database suffers from significant drawbacks. Forexample, a centralized database has a single point of failure. Inparticular, if there are no fault-tolerance considerations and ahardware failure occurs (for example a hardware, firmware, and/or asoftware failure), all data within the database is lost and work of allusers is interrupted. In addition, centralized databases are highlydependent on network connectivity. As a result, the slower theconnection, the amount of time needed for each database access isincreased. Another drawback is the occurrence of bottlenecks when acentralized database experiences high traffic due to a single location.Furthermore, a centralized database provides limited access to databecause only one copy of the data is maintained by the database. As aresult, multiple devices cannot access the same piece of data at thesame time without creating significant problems or risk overwritingstored data. Furthermore, because a database storage system has minimalto no data redundancy, data that is unexpectedly lost is very difficultto retrieve other than through manual operation from back-up storage.

Blockchain storage resolves some of the deficiencies of traditionalstorage systems. One of the benefits of blockchain is that it isdecentralized and thus highly fault-tolerant meaning that the blockchaincan continue to operate properly even when one or some of the componentshave failed. Additional benefits supported by blockchain include animmutable record, lack of a central authority, security, smartcontracts, and the like, which are not commonly found in traditionaldatabases. In order to enforce these properties, blockchain systems relyon hashes to secure data that is transmitted among the parties andstored on the blockchain. However, a typical blockchain hash can consumesignificant resources. As such, what is needed is an improved mechanismfor securing data within the blockchain.

SUMMARY

One example embodiment provides a system that includes one or more of anetwork interface configure to receive a location of an output stored ona data structure of a blockchain, where the location comprises a path ofhashes generated by a reduced-step hash instead of a full-step hash ofthe blockchain, and a processor configured to one or more of perform anapproximate hash verification on the path of hashes based on thereduced-step hash values to verify whether the output is unused, and, inresponse to a determination that the output is unused as a result of theapproximate hash verification, approve a use of the output by a clientassociated with the output.

Another example embodiment provides a method that includes one or moreof receiving a location of an output stored on a data structure of ablockchain, where the location comprises a path of hashes generated by areduced-step hash instead of a full-step hash of the blockchain,performing an approximate hash verification on the path of hashes basedon the reduced-step hash values to verify whether the output is unused,and in response to a determination that the output is unused as a resultof the approximate hash verification, approving a use of the output by aclient associated with the output.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of receiving a location of an outputstored on a data structure of a blockchain, where the location comprisesa path of hashes generated by a reduced-step hash instead of a full-stephash of the blockchain, performing an approximate hash verification onthe path of hashes based on the reduced-step hash values to verifywhether the output is unused, and in response to a determination thatthe output is unused as a result of the approximate hash verification,approving a use of the output by a client associated with the output.

Another example embodiment provides a system that includes one or moreof a network interface configured to receive a hashed identifier of anoutput stored on a data structure of a blockchain, where the hashedidentifier is generated by a reduced-hash instead of a full-hash of theblockchain, and a processor configured to perform an approximate hashverification on the hashed identifier based on the reduced-hash toverify whether the output is unused and in response to a determinationthat the output is unused as a result of the approximate hashverification, approve a use of the output by a client associated withthe output.

Another example embodiment provides a method that includes one or moreof receiving a hashed identifier of an output stored on a data structureof a blockchain, where the hashed identifier is generated by areduced-step hash instead of a full-step hash of the blockchain,performing an approximate hash verification on the hashed identifierbased on the reduced-step hash to verify whether the output is unused,and in response to a determination that the output is unused as a resultof the approximate hash verification, approving a use of the output by aclient associated with the output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a hash process for generating afull-step hash and a reduced-step hash according to example embodiments.

FIG. 2A is a diagram illustrating an example blockchain architectureconfiguration, according to example embodiments.

FIG. 2B is a diagram illustrating a blockchain transactional flow amongnodes, according to example embodiments.

FIG. 3A is a diagram illustrating a permissioned network, according toexample embodiments.

FIG. 3B is a diagram illustrating another permissioned network,according to example embodiments.

FIG. 3C is a diagram illustrating a permissionless network, according toexample embodiments.

FIGS. 4A-4B are diagrams illustrating a process of storing data andperforming an approximate hash verification of the stored data accordingto example embodiments.

FIG. 4C is a diagram illustrating a blockchain node performing arecovery operation via an approximate hash verification, according toexample embodiments.

FIG. 4D is a diagram illustrating a process of verifying an unspenttransaction via an approximate hash verification, according to exampleembodiments.

FIG. 4E is a diagram illustrating a process of storing a data file onblockchain based on a reduced-step hash according to exampleembodiments.

FIG. 4F is a diagram illustrating a process of committing data toblockchain based on an approximate verification according to exampleembodiments.

FIG. 4G is a diagram illustrating an endorsement process includingapproximate hash verification according to example embodiments.

FIG. 5A is a diagram illustrating a method of storing a reduced-stephash of a transaction on a blockchain according to example embodiments.

FIG. 5B is a diagram illustrating a method of performing an approximatehash verification of a transaction stored on a blockchain according toexample embodiments.

FIG. 5C is a diagram illustrating a method of a failed blockchain nodeperforming recovery based on approximate hash verification according toexample embodiments.

FIG. 5D is a diagram illustrating a method of transmitting a sequence ofblocks with reduced-step hashes according to example embodiments.

FIG. 5E is a diagram illustrating a method of determining whether atransaction is unspent based on an approximate hash verificationaccording to example embodiments.

FIG. 5F is a diagram illustrating another method of determining whethera transaction is unspent based on an approximate hash verificationaccording to example embodiments.

FIG. 5G is a diagram illustrating a method of storing a reduced-stephash of a media file on a blockchain according to example embodiments.

FIG. 5H is a diagram illustrating a method of performing an approximatehash verification on a media file stored on blockchain according toexample embodiments.

FIG. 5I is a diagram illustrating a method of approximate hashverification among endorser nodes according to example embodiments.

FIG. 5J is a diagram illustrating a method of endorsing a transactionwith a reduced-step hash verification according to example embodiments.

FIG. 5K is a diagram illustrating a method of performing an approximatehash verification on a data block according to example embodiments.

FIG. 5L is a diagram illustrating a method of ordering reduced-stephashes of transactions in a data block according to example embodiments.

FIG. 6A is a diagram illustrating an example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6B is a diagram illustrating another example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6C is a diagram illustrating a further example system configured toutilize a smart contract, according to example embodiments.

FIG. 6D is a diagram illustrating yet another example system configuredto utilize a blockchain, according to example embodiments.

FIG. 7A is a diagram illustrating a process of a new block being addedto a distributed ledger, according to example embodiments.

FIG. 7B is a diagram illustrating data contents of a new data block,according to example embodiments.

FIG. 7C is a diagram illustrating a blockchain for digital content,according to example embodiments.

FIG. 7D is a diagram illustrating a block which may represent thestructure of blocks in the blockchain, according to example embodiments.

FIG. 8A is a diagram illustrating an example blockchain which storesmachine learning (artificial intelligence) data, according to exampleembodiments.

FIG. 8B is a diagram illustrating an example quantum-secure blockchain,according to example embodiments.

FIG. 9 is a diagram illustrating an example system that supports one ormore of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined or removed in any suitablemanner in one or more embodiments. For example, the usage of the phrases“example embodiments”, “some embodiments”, or other similar language,throughout this specification refers to the fact that a particularfeature, structure, or characteristic described in connection with theembodiment may be included in at least one embodiment. Thus, appearancesof the phrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined orremoved in any suitable manner in one or more embodiments. Further, inthe diagrams, any connection between elements can permit one-way and/ortwo-way communication even if the depicted connection is a one-way ortwo-way arrow. Also, any device depicted in the drawings can be adifferent device. For example, if a mobile device is shown sendinginformation, a wired device could also be used to send the information.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof networks and data. Furthermore, while certain types of connections,messages, and signaling may be depicted in exemplary embodiments, theapplication is not limited to a certain type of connection, message, andsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which provide anapproximate hash verification for blockchain.

In one embodiment the system utilizes a decentralized database (such asa blockchain) that is a distributed storage system, which includesmultiple nodes that communicate with each other. The decentralizeddatabase includes an append-only immutable data structure resembling adistributed ledger capable of maintaining records between mutuallyuntrusted parties. The untrusted parties are referred to herein as peersor peer nodes. Each peer maintains a copy of the database records and nosingle peer can modify the database records without a consensus beingreached among the distributed peers. For example, the peers may executea consensus protocol to validate blockchain storage transactions, groupthe storage transactions into blocks, and build a hash chain over theblocks. This process forms the ledger by ordering the storagetransactions, as is necessary, for consistency. In various embodiments,a permissioned and/or a permissionless blockchain can be used. In apublic or permission-less blockchain, anyone can participate without aspecific identity. Public blockchains can involve native cryptocurrencyand use consensus based on various protocols such as Proof of Work(PoW). On the other hand, a permissioned blockchain database providessecure interactions among a group of entities which share a common goalbut which do not fully trust one another, such as businesses thatexchange funds, goods, information, and the like.

This system can utilize a blockchain that operates arbitrary,programmable logic, tailored to a decentralized storage scheme andreferred to as “smart contracts” or “chaincodes.” In some cases,specialized chaincodes may exist for management functions and parameterswhich are referred to as system chaincode. The application can furtherutilize smart contracts that are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes, which is referred to as anendorsement or endorsement policy. Blockchain transactions associatedwith this application can be “endorsed” before being committed to theblockchain while transactions, which are not endorsed, are disregarded.An endorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

This system can utilize nodes that are the communication entities of theblockchain system. A “node” may perform a logical function in the sensethat multiple nodes of different types can run on the same physicalserver. Nodes are grouped in trust domains and are associated withlogical entities that control them in various ways. Nodes may includedifferent types, such as a client or submitting-client node whichsubmits a transaction-invocation to an endorser (e.g., peer), andbroadcasts transaction-proposals to an ordering service (e.g., orderingnode). Another type of node is a peer node which can receive clientsubmitted transactions, commit the transactions and maintain a state anda copy of the ledger of blockchain transactions. Peers can also have therole of an endorser, although it is not a requirement. Anordering-service-node or orderer is a node running the communicationservice for all nodes, and which implements a delivery guarantee, suchas a broadcast to each of the peer nodes in the system when committingtransactions and modifying a world state of the blockchain, which isanother name for the initial blockchain transaction which normallyincludes control and setup information.

This system can utilize a ledger that is a sequenced, tamper-resistantrecord of all state transitions of a blockchain. State transitions mayresult from chaincode invocations (i.e., transactions) submitted byparticipating parties (e.g., client nodes, ordering nodes, endorsernodes, peer nodes, etc.). Each participating party (such as a peer node)can maintain a copy of the ledger. A transaction may result in a set ofasset key-value pairs being committed to the ledger as one or moreoperands, such as creates, updates, deletes, and the like. The ledgerincludes a blockchain (also referred to as a chain) which is used tostore an immutable, sequenced record in blocks. The ledger also includesa state database which maintains a current state of the blockchain.

This system can utilize a chain that is a transaction log which isstructured as hash-linked blocks, and each block contains a sequence ofN transactions where N is equal to or greater than one. The block headerincludes a hash of the block's transactions, as well as a hash of theprior block's header. In this way, all transactions on the ledger may besequenced and cryptographically linked together. Accordingly, it is notpossible to tamper with the ledger data without breaking the hash links.A hash of a most recently added blockchain block represents everytransaction on the chain that has come before it, making it possible toensure that all peer nodes are in a consistent and trusted state. Thechain may be stored on a peer node file system (i.e., local, attachedstorage, cloud, etc.), efficiently supporting the append-only nature ofthe blockchain workload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Since thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

Cryptographic hashing is a basic building block that is used extensivelyin blockchain systems. For example, a block hash (hash of a currentblock) is included in a next block. As another example, transactions arehashed and stored on a data structure (e.g., a Merkle tree) within ablock. As another example, digital signatures involve signing a hash ofthe message with private key, which in turn is used extensively in allcommunication, endorsements, client transaction submissions, and thelike. As another example, document hashes may be stored as part of smartcontract state, and verified upon retrieval. As another example, ablockchain fabric may store actual data within an off-chain data storage(side storage) while keeping a hash of the data within a publicblockchain.

Blockchain is built to be extremely fault tolerant. For example, dataand smart contract computation is replicated, with multiple nodesverifying transactions. In addition, all digital signatures for messagesare verified by multiple nodes. As another example, transaction andblock hashes are checked by all peer nodes. An endorsement policy can beused to ensure that sufficiently many nodes agree on client'sauthorization and correctness of transaction. Because of thefault-tolerance supported by blockchain, even if some nodes fail, thecorrect nodes will continue to ensure the system is working correctly.

The example embodiments introduce the concept of approximate hashverification to blockchain. When a hash of a data item (transaction,message, file, etc.), the creator may generate a full-step hash and areduced-step hash of the data item. Here, the reduced-step hash may bethe same hash function being applied as the full-step hash, but may beapplied for fewer steps than the full-step hash. As a non-limitingexample, the full-step hash may be applied for 64 steps while areduced-step hash may be applied for only 48 steps. Therefore, averifying entity may choose whether to verify the full-step hash (forfull verification) or the reduced-step hash (for approximateverification). This decision may be random, dictated by policy,predetermined, periodic, or the like. The approximate verification cansave significant computation for the node involved.

A potential setback of the approximate verification is a very slightincrease in the chance that an incorrect result/calculation may begenerated in comparison to the full-hash verification. However, becauseof the fault-tolerant properties of the blockchain, any mistakes(although very rare) may be corrected by other nodes on the blockchainthat do not perform the approximate verification.

Hashing in blockchain refers to the process of having an input item ofwhatever length reflecting an output item of a fixed length. As oneexample, transactions of varying lengths may be run through a givenhashing algorithm which generates an output that is of a fixed length.That is, the output is the same length regardless of the length of theinput transaction. The output is referred to as a hash. A common hashingalgorithm used on blockchain is Secure Hashing Algorithm 256 (commonlyshortened to SHA-256), however, many others are possible such as MD5(message digest algorithm), and the like. In SHA-256, hashing gives anoutput result of a fixed length (i.e., 256-bits length or 32 bytes).This is always the case whether the transaction is just a single word ora complex transaction with huge amounts of data. What this means is thatkeeping track of a transaction becomes easier when you can recall/tracethe hash. The size of the hash will depend on the hash functionutilized, but the out using a particular hashing algorithm will be of aspecific size.

For a cryptographic hash function to be considered secure, it has toportray certain characteristics or properties. For example, the hashfunction may have a fixed or specific output (deterministic). It doesn'tmatter what number of times a given input is processed using a hashfunction; the result should always of the same length. The hashes willbe random and of different patterns, but the same size/length. Asanother example, the hash function may be one that performs quickcomputations for every data input. It may be difficult to find the inputdata for a hash, but computing or calculating the hash should ideally bevery fast. As another example, the hash function may be one-way(pre-image resistant). Here, given a hash of a particular transaction,it should be virtually impossible or practically infeasible to determinethe original input data using this output. As another example, the hashfunction may be randomized in that the hash function produces differentoutputs for every input, even if the input data differs by only a digitor letter. As another example, the hash function may becollision-resistant in that different inputs do not create a same orsimilar output. The examples herein may refer to SHA-256, MD5, or thelike, but these should not be construed as limiting the types of hashfunctions that can be used by the system herein.

Some benefits of the instant solutions described and depicted hereininclude reduced computational effort by one or more nodes within ablockchain while still maintaining the overall correctness and securityof the blockchain. Furthermore, the speed at which a reduced-step hashand corresponding approximate hash verification are significantly fasterthan a full-step hash and a full-step hash verification. The approximatehash verification may be performed by some, but not all nodes, within ablockchain system. Therefore, the full-hash verification can be used toconfirm and correct any mistakes, although rare. Furthermore, thereduced-step hash can be created without any additional computationbecause the same hash function may be used. Therefore, the reduced-stephash may be generated while generating the full-step hash. For example,the reduced-step hash may be created by applying a hash function for 48steps while the full-step hash may be created by applying the hashfunction for another 16 steps (64 steps total), but embodiments are notlimited thereto.

According to various aspects, even if a node applies approximate hashverification and the hash verification is incorrect, there is sufficientfault tolerance in the blockchain system to counter the incorrectness.It is similar to when a peer fails or acts maliciously, which will notaffect the system's correctness. Furthermore, approximate hashverification permits improved performance of the system (e.g., lessprocessor computation on hash verification and more processorcomputation on other blockchain processes). Furthermore, the proposedtechnique can be applied to any system and instance of hash verificationfor which the system has in-built fault tolerance (for both theindividual peer and the overall system). In addition, the blockchainplatform may stipulate how many full nodes (non-approximating) must bepresent to ensure robustness/fault tolerance.

In the examples herein, the node performing the approximate hashverification may be incorrect. In this case, the blockchain continues tofunction correctly because the platform can stipulate a minimum numberof peers that must perform full-step hash verification. In this case,the other peers (full-step hash verifiers) would detect the verificationcorrectly. The faulty peer can now check the blockchain state (afterconsensus with other nodes) and detect that it had made an error inadmitting/refusing that transaction, when in fact other nodes came to adifferent conclusion.

FIG. 1 illustrates a hash process 100 for generating a full-step hashand a reduced-step hash according to example embodiments. Referring toFIG. 1, a message 110 is converted into a cryptographic hash 130. Manypopular hash functions include the following: (i) a particularnon-linear function is chosen, (ii) the selected non-linear function isapplied repeatedly on the input for several steps or rounds, and (iii)after repeating this for several steps (say 64 steps), the output willlook very different from the original input such that even a smalldifference in the original input would be magnified by the repeatedapplication of the non-linear function, to produce a very differentoutput (hashes of two similar looking messages will be very different).The reason to repeat the hash function for a large number of rounds isto prevent security attacks. Security properties of the popular hashfunctions when run for fewer number of steps have been widely studied.

As shown in FIG. 1, the message 110 (transaction, data item, etc.) isbroken up into a plurality of smaller blocks 112. In this model, themessage 110 may be padded and divided into blocks 112 of uniform length.The blocks 112 are then processed sequentially with a hash function F(compression function) 122. For example, the system may create an inputwhose size is a multiple of a fixed number (e.g. 512 or 1024) becausecompression functions cannot handle inputs of arbitrary size. The hashfunction then breaks the result into blocks of fixed size 112, andprocesses them one at a time with the compression function 122, eachtime combining a block of the input with the output of the previousround.

In order to make the construction secure, messages may be padded with apadding that encodes the length of the original message. This is calledlength padding or Merkle-Damgard strengthening. Starting with an initialblock, hash function 122 repeatedly generates a new intermediate hashvalue from the previous one and a new message block. The output of thefinal compression function is the hash 130 of the message.

In FIG. 1, the one-way compression function is denoted by F 122, andtransforms two fixed length inputs to an output of the same size as oneof the inputs. The algorithm starts with an initial value 121, alsoreferred to as an initialization vector (IV). The initial value 121 is afixed value (algorithm or implementation specific). For each block 112,the compression (or compacting) function F 122 takes the result so far,combines it with the message block, and produces an intermediate result.The last block is padded with zeros as needed and bits representing thelength of the entire message are appended.

To create the full-step hash, the function F 122 may be applied a firstnumber of times, for example, 64 rounds, etc. Meanwhile, to create thereduced-step hash, the function F 122 may be applied a second number oftimes that is less than the first number of times, for example, 48rounds, etc. When an entity creating the hash (such as the client, etc.)provides the hash to the blockchain nodes, etc., the entity shouldprovide not only the full-step hash but also the reduced-step hash. Thatis, the example embodiments include an entity providing an original hashfunction algorithm (e.g., 64 rounds, etc.), but also an intermediateresult from a reduced-step application (e.g., 48 rounds, etc.) of thesame algorithm. The computation effort for anyone else to verify thereduced-step hash function would be lesser than the effort for theoriginal function.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, a read set226 may be processed by one or more processing entities (e.g., virtualmachines) included in the blockchain layer 216. The result may include awrite set 228 for storage on the blockchain ledger. The physicalinfrastructure 214 may be utilized to retrieve any of the data orinformation described herein.

A smart contract may be created via a high-level application andprogramming language, and then written to a block in the blockchain. Thesmart contract may include executable code which is registered, stored,and/or replicated with a blockchain (e.g., distributed network ofblockchain peers). A transaction is an execution of the smart contractcode which can be performed in response to conditions associated withthe smart contract being satisfied. The executing of the smart contractmay trigger a trusted modification(s) to a state of a digital blockchainledger. The modification(s) to the blockchain ledger caused by the smartcontract execution may be automatically replicated throughout thedistributed network of blockchain peers through one or more consensusprotocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto the blockchain. The code may be used to create a temporary datastructure in a virtual machine or other computing platform. Data writtento the blockchain can be public and/or can be encrypted and maintainedas private. The temporary data that is used/generated by the smartcontract is held in memory by the supplied execution environment, thendeleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. As described herein, the chaincode may beprogram code deployed on a computing network, where it is executed andvalidated by chain validators together during a consensus process. Thechaincode receives a hash and retrieves from the blockchain a hashassociated with the data template created by use of a previously storedfeature extractor. If the hashes of the hash identifier and the hashcreated from the stored identifier template data match, then thechaincode sends an authorization key to the requested service. Thechaincode may write to the blockchain data associated with thecryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250between nodes of the blockchain in accordance with an exampleembodiment. Referring to FIG. 2B, the transaction flow may include atransaction proposal 291 sent by an application client node 260 to anendorsing peer node 281. The endorsing peer 281 may verify the clientsignature and execute a chaincode function to initiate the transaction.The output may include the chaincode results, a set of key/valueversions that were read in the chaincode (read set), and the set ofkeys/values that were written in chaincode (write set). The proposalresponse 292 is sent back to the client 260 along with an endorsementsignature, if approved. The client 260 assembles the endorsements into atransaction payload 293 and broadcasts it to an ordering service node284. The ordering service node 284 then delivers ordered transactions asblocks to all peers 281-283 on a channel. Before committal to theblockchain, each peer 281-283 may validate the transaction. For example,the peers may check the endorsement policy to ensure that the correctallotment of the specified peers have signed the results andauthenticated the signatures against the transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates thetransaction 291 by constructing and sending a request to the peer node281, which is an endorser. The client 260 may include an applicationleveraging a supported software development kit (SDK), which utilizes anavailable API to generate a transaction proposal. The proposal is arequest to invoke a chaincode function so that data can be read and/orwritten to the ledger (i.e., write new key value pairs for the assets).The SDK may serve as a shim to package the transaction proposal into aproperly architected format (e.g., protocol buffer over a remoteprocedure call (RPC)) and take the client's cryptographic credentials toproduce a unique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction and broadcasts the transaction proposaland response within a transaction message to the ordering node 284. Thetransaction may contain the read/write sets, the endorsing peerssignatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks of the transaction are delivered from the ordering node 284to all peer nodes 281-283 on the channel. The transactions 294 withinthe block are validated to ensure any endorsement policy is fulfilledand to ensure that there have been no changes to ledger state for readset variables since the read set was generated by the transactionexecution. Transactions in the block are tagged as being valid orinvalid. Furthermore, in step 295 each peer node 281-283 appends theblock to the channel's chain, and for each valid transaction the writesets are committed to current state database. An event is emitted, tonotify the client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3A illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture.In this example, a blockchain user 302 may initiate a transaction to thepermissioned blockchain 304. In this example, the transaction can be adeploy, invoke, or query, and may be issued through a client-sideapplication leveraging an SDK, directly through an API, etc. Networksmay provide access to a regulator 306, such as an auditor. A blockchainnetwork operator 308 manages member permissions, such as enrolling theregulator 306 as an “auditor” and the blockchain user 302 as a “client”.An auditor could be restricted only to querying the ledger whereas aclient could be authorized to deploy, invoke, and query certain types ofchaincode.

A blockchain developer 310 can write chaincode and client-sideapplications. The blockchain developer 310 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 312 in chaincode, the developer 310 could use anout-of-band connection to access the data. In this example, theblockchain user 302 connects to the permissioned blockchain 304 througha peer node 314. Before proceeding with any transactions, the peer node314 retrieves the user's enrollment and transaction certificates from acertificate authority 316, which manages user roles and permissions. Insome cases, blockchain users must possess these digital certificates inorder to transact on the permissioned blockchain 304. Meanwhile, a userattempting to utilize chaincode may be required to verify theircredentials on the traditional data source 312. To confirm the user'sauthorization, chaincode can use an out-of-band connection to this datathrough a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network320, which features a distributed, decentralized peer-to-peerarchitecture. In this example, a blockchain user 322 may submit atransaction to the permissioned blockchain 324. In this example, thetransaction can be a deploy, invoke, or query, and may be issued througha client-side application leveraging an SDK, directly through an API,etc. Networks may provide access to a regulator 326, such as an auditor.A blockchain network operator 328 manages member permissions, such asenrolling the regulator 326 as an “auditor” and the blockchain user 322as a “client”. An auditor could be restricted only to querying theledger whereas a client could be authorized to deploy, invoke, and querycertain types of chaincode.

A blockchain developer 330 writes chaincode and client-sideapplications. The blockchain developer 330 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 332 in chaincode, the developer 330 could use anout-of-band connection to access the data. In this example, theblockchain user 322 connects to the network through a peer node 334.Before proceeding with any transactions, the peer node 334 retrieves theuser's enrollment and transaction certificates from the certificateauthority 336. In some cases, blockchain users must possess thesedigital certificates in order to transact on the permissioned blockchain324. Meanwhile, a user attempting to utilize chaincode may be requiredto verify their credentials on the traditional data source 332. Toconfirm the user's authorization, chaincode can use an out-of-bandconnection to this data through a traditional processing platform 338.

In some embodiments, the blockchain herein may be a permissionlessblockchain. In contrast with permissioned blockchains which requirepermission to join, anyone can join a permissionless blockchain. Forexample, to join a permissionless blockchain a user may create apersonal address and begin interacting with the network, by submittingtransactions, and hence adding entries to the ledger. Additionally, allparties have the choice of running a node on the system and employingthe mining protocols to help verify transactions.

FIG. 3C illustrates a process 350 of a transaction being processed by apermissionless blockchain 352 including a plurality of nodes 354. Asender 356 desires to send payment or some other form of value (e.g., adeed, medical records, a contract, a good, a service, or any other assetthat can be encapsulated in a digital record) to a recipient 358 via thepermissionless blockchain 352. In one embodiment, each of the senderdevice 356 and the recipient device 358 may have digital wallets(associated with the blockchain 352) that provide user interfacecontrols and a display of transaction parameters. In response, thetransaction is broadcast throughout the blockchain 352 to the nodes 354.Depending on the blockchain's 352 network parameters the nodes verify360 the transaction based on rules (which may be pre-defined ordynamically allocated) established by the permissionless blockchain 352creators. For example, this may include verifying identities of theparties involved, etc. The transaction may be verified immediately or itmay be placed in a queue with other transactions and the nodes 354determine if the transactions are valid based on a set of network rules.

In structure 362, valid transactions are formed into a block and sealedwith a lock (hash). This process may be performed by mining nodes amongthe nodes 354. Mining nodes may utilize additional software specificallyfor mining and creating blocks for the permissionless blockchain 352.Each block may be identified by a hash (e.g., 256 bit number, etc.)created using an algorithm agreed upon by the network. Each block mayinclude a header, a pointer or reference to a hash of a previous block'sheader in the chain, and a group of valid transactions. The reference tothe previous block's hash is associated with the creation of the secureindependent chain of blocks.

Before blocks can be added to the blockchain, the blocks must bevalidated. Validation for the permissionless blockchain 352 may includea proof-of-work (PoW) which is a solution to a puzzle derived from theblock's header. Although not shown in the example of FIG. 3C, anotherprocess for validating a block is proof-of-stake. Unlike theproof-of-work, where the algorithm rewards miners who solve mathematicalproblems, with the proof of stake, a creator of a new block is chosen ina deterministic way, depending on its wealth, also defined as “stake.”Then, a similar proof is performed by the selected/chosen node.

With mining 364, nodes try to solve the block by making incrementalchanges to one variable until the solution satisfies a network-widetarget. This creates the PoW thereby ensuring correct answers. In otherwords, a potential solution must prove that computing resources weredrained in solving the problem. In some types of permissionlessblockchains, miners may be rewarded with value (e.g., coins, etc.) forcorrectly mining a block.

Here, the PoW process, alongside the chaining of blocks, makesmodifications of the blockchain extremely difficult, as an attacker mustmodify all subsequent blocks in order for the modifications of one blockto be accepted. Furthermore, as new blocks are mined, the difficulty ofmodifying a block increases, and the number of subsequent blocksincreases. With distribution 366, the successfully validated block isdistributed through the permissionless blockchain 352 and all nodes 354add the block to a majority chain which is the permissionlessblockchain's 352 auditable ledger. Furthermore, the value in thetransaction submitted by the sender 356 is deposited or otherwisetransferred to the digital wallet of the recipient device 358.

In the examples of FIGS. 4A-4G, various examples are provided in whichan approximate hash verification can be performed instead of or alongwith a full-step hash verification. The approximate hash verificationonly computes a reduced-step hash operation and does not execute all ofthe steps of the full-step hash operation. Therefore, the approximatehash verification is faster and consumes less resources. In order toenable the approximate hash verification, a client, node, etc.,submitting the hashed data may submit both the full-step hash of thedata and the reduced-step hash of the data. The reduced-step hash isgenerated using the same function as the full-step hash, but isperformed less times/rounds. Therefore, there is no additionalcomputation needed for the client, node, etc. to submit both thereduced-step hash and the full-step hash.

Hashing is used in many places in any blockchain protocol (e.g., digitalsignatures for all communication include hashes, hash of each block oftransactions is stored in the header of the next block, hash of smartcontract state is used to verify consistency of the ledger acrossdifferent nodes, the application can use a hash to verify that the datait recorded on the blockchain has not been tampered with, etc.) Wherevera hash is stored, the example embodiments may store a reduced-step hashinstead of or in addition to the full-step hash. This would permit anyverifier to either verify the full hash function output or thereduced-step hash function output.

FIGS. 4A-4B illustrate a process of storing data and performing anapproximate hash verification of the stored data according to exampleembodiments. In the example of FIG. 4A, during a process 400A, a client406 submits a transaction 405 to a blockchain 402 via a blockchain peernode 404. Here, the client 406 hashes the transaction 405 prior tosubmitting it to the peer node 404. In this example, the client 406submits both a reduced-step hash of the transaction 405 and a full-stephash of the transaction 405. In this example, the transaction 405 mayinclude any desired transaction for storage on the blockchain 402. Thetransaction (also referred to herein as a blockchain entry, storagerequest, etc.) may be between more than one party or may be associatedwith a single party.

Referring to FIG. 4B, a node e.g., the client node 406 or another node408, wants to verify that the transaction 405 has been recordedcorrectly on the blockchain 402. For example, the submitting client 406may desire to verify that the outputs of the transaction have beenregistered correctly (e.g., perform a transaction to transfer 10 tokensof currency, etc.) Here the client 406 may verify that a balance hasbeen correctly deducted by 10 tokens, etc. More generically, any clientapplication or blockchain node that submitted a transaction to beincluded in the blockchain, can check the hash of the transaction in theblock added to the chain to ensure that it has been added correctly.

In the processor 400B of FIG. 4B, the peer node 404 retrieves thereduced-step hash 409 of the transaction. In this case, the client 406may perform an approximate hash verification based on the reduced-stephash 409 instead of the full-step hash. Here, to perform the approximatehash verification, the client 406 may generate a local copy of thereduced-step hash of the transaction and compare it with the retrievedreduced-step hash 409 stored on the blockchain 402. If the locallygenerated reduced-step hash matches the retrieved reduced-step hash 409,the client 406 can verify that the transaction was recorded correctly.

FIG. 4C illustrates a process 410 of a blockchain node 411 performing arecovery operation via an approximate hash verification, according toexample embodiments. Referring to FIG. 4C, the blockchain node 411 maybe a peer node, an endorser node, an ordering node, a combinationthereof, or the like. In this example, the blockchain node 411 hasdetected an interruption that has occurred in the storage of block datawithin a local copy of the distributed ledger managed by the blockchainnode 411. Reasons for interruption include power outage/failure, corruptdata, malware/attack, and the like. In this example, the blockchain node411 may request recovery of the missed/corrupted data from one or moreother peer nodes such as peer nodes 412 and peer nodes 414 which alsostore a local copy of the distributed ledger.

In this example, the blockchain node 411 may recover the missed blocksfrom a first peer node 412. In this example, the first peer node 412 maystore a sequence of blocks 413 which are linked together throughreduced-step hashes instead of full-step hashes. In this case, a headeror other content of a block may be hashed (via the reduced-step hash)and stored in a next block to create a link between the blocks. When theblockchain node 411 receives the sequence 413 it may perform anapproximate hash verification and compare the hash of each transactionstored in the blocks and also the way it has been chained together (withthe hash of a block being present in the next block and so on) to verifythat the blocks have not been tampered with. Comparing these hashesprovides a guarantee to the recovering peer 411 that the data it hasreceived is the correct blockchain data and has not been tampered by thepeer it contacted to acquire the data.

As an optional process, the blockchain node 411 may retrieve a sequenceof blocks 415 from a second peer 414 which have been hashed and linkedtogether using a full-step hash. In this case, the sequence of blocks415 may be the same block content as the sequence of blocks 413 withfull-step hashes being performed instead of reduced-step hashes. Inresponse, the blockchain node 411 can verify that the hash of each blockis included in the next block using approximate hash verification, andalso verify that the hash of the blocks is as provided by the secondpeer 414 (optionally).

FIG. 4D illustrates a process 420 of verifying an unspent transactionvia an approximate hash verification, according to example embodiments.Various blockchain platforms employ an unspent transaction output model(UTXO), such as Bitcoin, Ethereum and Corda, for checking and preventingdouble spending. Here each peer node creates a Merkle tree of hashes oftransactions and stores the Merkle roots of each block. Every node alsomaintains a list of unspent transaction outputs (outputs that are notthe inputs for any other transaction).

Referring to FIG. 4D, a client, when submitting a transaction, needs toprove that their inputs are not yet spent. To do this, the client mayprove the transaction is unspent by providing a valid path in the Merkletree of a block that contains the input. Each peer by computing theMerkle root from the hashes provided, can verify that the UTXO hasn'tbeen spent yet. In the example of FIG. 4D, the transaction C is unspent.To verify this, the client may provide a path of reduced-step hashesincluding a reduced-step hash 421, a reduced-step hash 422, areduced-step hash 423, a reduced-step hash 424, and a root hash 425.Here, the root hash 425 includes a concatenation of the path ofreduced-step hashes 424, 423, 422, and 421. In this case, the peer maycompute the hash of all the entries in the Merkle path along with thereferenced transaction from the first hash 421 to the root hash 424 andcheck whether the result is indeed the Merkle root of the referencedblock (this proves that the referenced transaction is indeed atransaction on the blockchain).

In this example, each peer in the blockchain creates a Merkle tree ofhashes of all transactions for each block. Furthermore, the Merkle rootof the tree for each block is maintained as an identifier of the block.Each peer also maintains the list of UTXOs (unspent transactionoutputs). When a client submits a transaction this provides proof foreach of its inputs, that it is unspent. Here, for each of its inputs inits transaction, the client provides the location of the transactionoutput in the blockchain, that is being spent by this input. This isdone by providing the Merkle path of hashes, which when all hashedtogether with the transaction referenced, will produce the Merkle rootof the block containing this UTXO.

FIG. 4E illustrates a process 430 of storing a data file 432 onblockchain 444 based on a reduced-step hash according to exampleembodiments. In this example, a client 431 submits a data file 432 to apeer node 440 for storage on the blockchain 444. In this example, theclient 431 may subsequent determine whether the data file 432 (which maybe added within a blockchain transaction) has been tampered in any way.As a non-limiting example, the data file 431 may be a document, a video,an audio, a multi-media file, and the like. For example, a supplier mayadd an invoice document to the blockchain 444 as a transaction, forgoods it delivered to a manufacturer. The manufacturer, also has a copyof the invoice, can verify the transaction on blockchain to ensure thatits copy of the invoice is actually correct and has not been tamperedwith.

Referring to FIG. 4E, the peer node 440 may receive the data file 432 aswell as a reduced-step hash of the file 432 and a full-step hash of thedata file 432. In response, the peer node 440 may store a transaction434 including the full-step hash and the reduced-step hash on theblockchain 444. Meanwhile, the data file 432 may be stored off-chain ona database 442 to conserve storage space on the blockchain. However,embodiments are not limited thereto and the data file may be stored onthe blockchain 444. When the data file 432 is stored off-chain, the peernode 440 may store metadata of a location of the off-chain data filewithin the transaction 434 including the reduced-step hash and thefull-step hash.

Accordingly, the data file 432 may be added as a transaction 434 to theblockchain 444 or an external database by the client 431. In thisexample, the reduced-step hash of the data file 432 may be used toverify the data file 432 is correct. For example, when another user (notshown) needs to access this data file 432, the user can retrieve thereduced-step hash and perform an approximate hash verification to verifythe data file 432 is correct. In this case, the other user can generatea local copy of the reduced-step hash and compare it to the copy storedon the blockchain 444 to verify it has not been tampered with.

FIG. 4F illustrates a process 450 of committing data to blockchain basedon an approximate verification according to example embodiments. In thisexample, a client 451 submits a transaction to an ordering node 452. Theordering node may arrange the transaction in a data block 453 with othertransactions, and transmit the data block 453 to committing peer nodes454, 455, and 456 within the blockchain network. The benefit here isthat checking the authenticity of the client 451, integrity of themessage/block, and performing any access control (e.g., is the clientauthorized to invoke this particular smart contract transaction), can beperformed using approximate hash verification.

In this example, the client 451 may digitally sign the submittedtransaction with their private key (the digital signature is anencryption operation on the hash of the transaction, and could inaddition include the same encryption operation on the approximate hashas well). In this example, each of the committing peers 454-456 mayverify the digital signature using the public key of the client. Here,if the signature for the transaction matches that of the client, thepeer is assured that (a) no one other than the owner of the private key(the client) could have submitted the transaction, (b) no one alteredthe transaction from the time client signed it to when the peer receivedthe transaction guaranteeing integrity of the transaction submission,and (c) check if the client is authorized to perform this operation,e.g., is the client spending their own funds or trying to spend someoneelse's (the latter would be denied as invalid; the signature permitsthis check). In this case, one or more of the peers 454-456 may performan approximate hash verification check instead of the full hash-stepcheck, if the client 451 included both the reduced-step hash as well asthe original full-step hash of the transaction.

Furthermore, the blocks (including block 453) may be chained togetherusing reduced-step hashes instead of full-step hashes. Therefore, beforecommitting the block 453 to the blockchain (distributed ledger) thecommitting peer nodes 454-456 may perform an approximate hashverification on the chaining of the blocks and the transactions withinthe blocks.

FIG. 4G illustrates an endorsement process 460 which supportsapproximate hash verification according to example embodiments.Referring to FIG. 4G, a client 461 submits a transaction to a pluralityof endorser nodes 462, 463, and 464. In this example, the transaction issigned by the client 461. The client 461 producing the signatures mayproduce both the original full-step hash value of the signature and thereduced-step hash value of the signature. Each of the endorser peernodes 462, 463, and 464 may determine whether to verify just theapproximate signature or the full signature.

In the endorsement process 460, there are two signatures that areverified. Each endorser 462-464 verifies the client signature. In thiscase, one or more of the endorsers could verify the original hash, whileone or more other endorsers could verify just the approximate signature.Which endorser performs which verification may be defined in advance byan endorsement policy. Furthermore, the blockchain platform couldadditionally stipulate how many full nodes (non-approximating) must bepresent to ensure robustness/fault tolerance. For example, in additionto specifying k out of n endorsing peers must perform a full-stependorsement, the platform could specify that at most k′ out of kendorsers apply reduced-step endorsement (each endorser in their signedresponse includes whether or not they applied approximation). Duringconsensus, the blockchain protocol may specify maximum number of nodesthat apply approximation. The endorser node verifying the approximatehash gains time and computation cost over the one that verifies theoriginal.

In a second signature, each of the endorsers then execute thetransactions and digitally sign the output. When they do so, they canadd an approximate hash value as well, which is an intermediate stepoutput. All peers in the network verify all the endorser's signatures toensure all the endorsers have signed. Here again, peers can performeither a full verification or an approximate verification of all theendorser signatures for each transaction. If all signatures are valid,then the transaction is chosen to be committed to the ledger.

Whether or not an endorser performed an approximate verification can bedenoted by an additional flag in the endorsement response (or any otherconfirmation message) stating this as true or false. Alternatively, whena peer joins the network, it could join as an ‘approximate peer’informing other peers that it will only perform approximateverifications (e.g., a resource constrained node). This information mayor may not be recorded on the blockchain. The blockchain configurationcould also limit the number of such approximate peers in the network toensure reliability.

Although not shown in FIGS. 4A-4G, Another dimension on which theexample embodiments could be applied is in terms of which peers performapproximate verification. For example, an organization may run multiplepeers in a network. One of the peers can be a full peer whereas otherpeers perform approximate verifications. If they make an error, they canrefer to the full peer for the correct results. As another example, somepeers in the network may be resource constrained (including IoTdevices), which may find it difficult to keep pace with the other fullpeers. These resource constrained devices could perform approximateverifications to keep pace with the full peers in the network. Asanother example, peers can have a rotation policy on performingapproximate verification. For example, a first peer can performapproximate verification for blocks 1-10, a second peer for blocks11-20, and so on. This would permit each peer to save computation timeand collectively the network can operate faster than when every nodealways performed the full verification.

FIG. 5A illustrates a method 500A of storing a reduced-step hash of atransaction on a blockchain according to example embodiments. Forexample, the method 500A may be performed by a client application of ablockchain. Referring to FIG. 5A, in 501, the method may includetransmitting, from the client application, a message to one or moreblockchain nodes to store a storage request on a blockchain. Forexample, the message may include a full-step hash of the storage requestand a reduced-step hash of the storage request. In some embodiments, themethod may further include generating the full-step hash of the storagerequest by repeatedly performing a hash function on a data value of thestorage request a first predetermined number of times, and generatingthe reduced-step hash of the storage request by repeatedly performingthe hash function on the data value of the storage request a secondpredetermined number of times that is less than the first predeterminednumber of times.

In some embodiments, a length of a data value created by thereduced-step hash of the storage request is equal to a length of a datavalue created by the full-step hash of the storage request. In someembodiments, the reduced-step hash of the storage request may be storedwithin a Merkle tree data structure of the blockchain. In someembodiments, the reduced-step hash of the storage request may include areduced-step hash of a blockchain entry such as a transaction providedfrom the client.

In 502, the method may include receiving, from a blockchain node, arecordation confirmation indicating the reduced-step hash of the storagerequest is stored on the blockchain. Further, in 503, the method mayinclude verifying, by the client application, whether the recordation ofthe storage request is correct based on an approximate hash verificationof the reduced-step hash of the storage request. For example, theapproximate hash verification may include generating the reduced-stephash of the storage request and comparing it to the reduced-step hashstored on the blockchain for verification without generating thefull-step hash of the storage request. In some embodiments, the methodmay further include displaying a success notification via a user deviceof the client application, in response to the approximate hashverification of the reduced-step hash of the storage request beingsuccessful.

FIG. 5B illustrates a method 500B of performing an approximate hashverification of a transaction stored on a blockchain according toexample embodiments. For example, the method 500B may be performed by apeer node on a blockchain. Referring to FIG. 5B, in 506, the method mayinclude receiving, from a client application, a message with a storagerequest for storage on a blockchain, the message comprising a full-stephash of the storage request and a reduced-step hash of the storagerequest. Here, the full-step hash may be generated by the clientapplication repeatedly performing of a hash function on a data value ofthe storage request a first predetermined number of times, and thereduced-step hash may be generated by repeated performance of the hashfunction on the data value of the storage request a second predeterminednumber of times that is less than the first predetermined number oftimes.

In 507, the method may include determining, by the blockchain peer node,whether to store the storage request as the reduced-step hash or thefull-step hash. For example, the determination may be random,predetermined by blockchain policy, deterministic based on an identifierin the storage request, or the like. In 508, in response to determiningto store the storage request as the reduced-step hash, the method mayinclude committing the reduced-step hash of the storage request to ablock included in a hash-linked chain of blocks. In some embodiments, alength of a data value created by the reduced-step hash of the storagerequest is equal to a length of a data value created by the full-stephash of the storage request. In some embodiments, the committing mayinclude storing the reduced-step hash of the storage request within aMerkle tree data structure of the blockchain. In some embodiments, thereduced-step hash of the storage request may include a reduced-step hashof a blockchain entry such as a transaction.

FIG. 5C illustrates a method 510A of a failed blockchain node performingrecovery based on approximate hash verification according to exampleembodiments. Peer nodes may fail for all sorts of reasons such as poweroutage, malicious attack, maintenance, and the like. To recover missedblocks, the failed node may perform the method of FIG. 5C. Referring toFIG. 5C, in 511, the method may include receiving, from a blockchainpeer node, a sequence of blocks stored in a hash-linked chain of blockson a distributed ledger, where each block in the sequence of blocksincludes a reduced-step hash of block content from a previous block inthe sequence. In some embodiments, the method may further includetransmitting, to the blockchain peer node, a request for the sequence ofblocks in response to a crash at a failed blockchain peer node, or inresponse to a recovery operation at another blockchain peer node.

In 512, the method may include performing an approximate hashverification on the reduced-step hashes stored among the sequence ofblocks. Further, in 513, the method may include determining whether thesequence of blocks has been tampered with based on the approximate hashverification on the reduced-step hashes. If the blocks have not beentampered with, the failed node can determine that the blocks are correctand store the blocks on the blockchain thereof. The approximate hashverification can compare the reduced-step hash within a block in thesequence to content included in a previous block linked by thereduced-step hash to determine whether the hash is correct. In this way,the node can perform a verification of each of the hash links using anapproximate hash verification instead of a full-hash verification.

In some embodiments, the method may further include receiving, from asecond blockchain peer node, a second version of the sequence of blockswhere each block in the second version of the sequence of blocksincludes a full-step hash of block content from a previous block in thesequence, wherein the full-step hash comprises repeated performance of ahash function on hash content a greater number of times than thereduced-step hash. In some embodiments, the method may further includeverifying the sequence of blocks which includes the reduced-step hashesreceived from the blockchain peer node based on the second version ofthe sequence of blocks which includes the full-step hashes received fromthe second blockchain peer node. In some embodiments, each block amongthe sequence of blocks may include a reduced-step hash of a header of aprevious block in the chain. To verify the link, the node may verify thereduced-step hash of the header by calculating the same reduced-stephash. In some embodiments, the approximate hash verification may verify,for each block in the sequence, that a reduced-step hash of a header ofa previous block in the sequence is included the respective block.

FIG. 5D illustrates a method 510B of transmitting a sequence of blockswith reduced-step hashes according to example embodiments. For example,the method 510B may be performed by a recovery node on a blockchain forrecovering peer nodes that fail. In 516, the method may include storinga hash-linked chain of blocks via a blockchain ledger, wherein thehash-linked chain of blocks are linked together via hash content that isgenerated using a reduced-step hash. Here, the blocks are linked withreduced-step hashes of a previous block instead of full-step hashes.

In 517, the method may further include receiving a request from a failedpeer node for a sequence of blocks from among the stored hash-linkedchain of blocks. Failure may occur when a node is offline or records acorrupt sequence of blocks. In 518, the method may include transmittingthe requested sequence of blocks which are linked together usingreduced-step hash content to the failed peer node.

In some embodiments, the method may further include receiving blockcontent of the hash-linked chain of blocks which includes a full-stephash of the block content and the reduced-step hash of the blockcontent. In some embodiments, the full-step hash of the block contentmay be created by repeated performance of a hash function a firstpredetermined number of times, and the reduced-step hash of the blockcontent is created by repeated performance of the hash function a secondpredetermined number of times that is less than the first predeterminednumber of times. In some embodiments, the method may further includedetermining to transmit the sequence of blocks that are linked togethervia the reduced-step hash content rather than the full-step hash contentbased on a predetermined blockchain policy. In some embodiments, eachblock among the sequence of blocks may include a reduced-step hash of aheader of a previous block in the chain.

FIG. 5E illustrates a method 520A of determining whether a transactionis unspent based on an approximate hash verification according toexample embodiments. For example, the unspent transaction verificationmay be performed by a peer node. Referring to FIG. 5E, in 521, themethod may include receiving a location of an output stored on a datastructure of a blockchain, where the location comprises a path of hashesgenerated by a reduced-step hash instead of a full-step hash of theblockchain. In this example, the location may include a block within ahash-linked chain of blocks. The location may be identified through asequence of hashes that are based on a path of a transaction to a rootnode in a data structure storing the transaction. In this example, thepath of hashes, when hashed together, may produce an identifier of adata block in the blockchain storing the unused output. In this example,the full-step hash may include repeated performance of a hash function afirst predetermined number of times, and the reduced-step hash mayinclude repeated performance of the hash function a second predeterminednumber of times that is less than the first predetermined number oftimes.

In 522, the method may include performing an approximate hashverification on the path of hashes based on the reduced-step hash valuesto verify whether the output is unused. Furthermore, in response to adetermination that the output is unused as a result of the approximatehash verification, in 523 the method may further include approving a useof the output by a client associated with the output. In someembodiments, the approximate hash verification may include generating areduced-step hash of each node in the path, and verifying whether thegenerated result is the identifier of the data block.

In some embodiments, the path of hashes may include a path of hashes ona Merkle tree from a node corresponding to a transaction to a root nodeof the Merkle tree. In some embodiments, each node on the path mayinclude a reduced-step hash of data from its child nodes in the datastructure. In some embodiments, the method may further includepreventing the use of the output, in response to determining that theoutput is used as a result of the approximate hash verification.

FIG. 5F illustrates another method 520B of determining whether atransaction is unspent based on an approximate hash verificationaccording to example embodiments. Referring to FIG. 5F, in 526, themethod may include receiving a hashed identifier of an output stored ona data structure of a blockchain, where the hashed identifier isgenerated by a reduced-step hash instead of a full-step hash of theblockchain. In this example, the hashed identifier may include anidentification of a data block in the blockchain storing the unusedoutput.

In 527, the method may include performing an approximate hashverification on the hashed identifier based on the reduced-step hash toverify whether the output is unused. In response to a determination thatthe output is unused as a result of the approximate hash verification,in 528 the method may include approving a use of the output by a clientassociated with the output. In some embodiments, the hashed identifiermay be generated by performing a chain of reduced-step hashes based on apath of the output stored in a blockchain data structure. In someembodiments, the method may further include, in response to determiningthat the output is used as a result of the approximate hashverification, preventing the use of the output. In some embodiments, themethod may further include storing hashed identifiers of a plurality ofdata blocks and identifiers of the outputs stored in each data block.

FIG. 5G illustrates a method 530A of storing a reduced-step hash of amedia file on a blockchain according to example embodiments. Forexample, the method may be performed by a peer node storing a hash ofthe media file. Referring to FIG. 5G, in 531 the method may includestoring a full-step hash of a data file and a reduced-step hash of thedata file within a data block of a hash-linked chain of blocks of ablockchain. For example, the data file may include one or more of anaudio file, a video file, a document, an image, and a multi-media file.

In 532, the method may include receiving a request from a clientapplication to verify the data file. In response, in 533, the method mayinclude determining whether to provide the full-step hash of the datafile or the reduced-step hash of the data file based on the request, andin response to determining to provide the reduced-step hash, in 534 themethod may include transmitting the reduced-step hash of the data fileto the client application. In these examples, the full-step hash of thedata file may be generated by repeated performance of a hash function onthe data file a first predetermined number of times, and thereduced-step hash of the data file may be generated by repeatedperformance of the hash function on the data file a second predeterminednumber of times that is less than the first predetermined number oftimes.

In some embodiments, the determining to provide the reduced-step hash ofthe data file is based on one or more of a predetermined policy of theblockchain and a notification element within the received request. Asanother example, the determining may be based on an identifier withinthe request from the client (or other node), or the like. In someembodiments, the full-step hash of the data file and the reduced-stephash of the data file are both received from a different clientapplication than the client application that submitted the request.

FIG. 5H illustrates a method 530B of performing an approximate hashverification on a media file stored on blockchain according to exampleembodiments. The method may be performed by a client node, a peer node,or the like. In 536, the method may include receiving a hashed data filefrom a blockchain peer node, where data of the hashed data file ispreviously stored within a hash-linked chain of blocks on a blockchain.In this example, the hashed data file may include a hash of one or moreof an audio file, a video file, a document, an image, and a multi-mediafile.

In 537, the method may include detecting whether the hashed data filehas been hashed using a full-step hash or a reduced-step hash. Inresponse to a detecting that the hashed data file is hashed using thereduced-step hash, in 538 the method may include determining whether thehashed data file has been tampered with through an approximate hashverification of the hashed data file. In some embodiments, the full-stephash may include repeated performance of a hash function on the datafile a first predetermined number of times, and the reduced-step hashcomprises repeated performance of the hash function on the data file asecond predetermined number of times that is less than the firstpredetermined number of times.

In some embodiments, a length of a data value created by thereduced-step hash applied to the data file is equal to a length of adata value created by the full-step hash applied to the data file. Insome embodiments, the determining may include generating a reduced-stephash of a local copy of the data file and verifying the retrieved hasheddata file based on the reduced-step hash of the local copy of the datafile. In some embodiments, the data file may include a media file thatis stored off-chain while a hash result of the hashed data file isstored within a data block among the hash-linked chain of blocks.

FIG. 5I illustrates a method 540A of approximate hash verification amongendorser nodes according to example embodiments. For example, the method540A may be performed by a client node receiving endorsements from aplurality of peer (endorser nodes) on the blockchain. Referring to FIG.5I, in 541, the method may include transmitting, from a clientapplication, a proposed storage request to a plurality of endorser nodesof a blockchain. Here, the transmitting may include transmitting afull-step hash of the proposed storage request signed by the clientapplication and a reduced-step hash of the storage request signed by theclient application to the plurality of endorser nodes.

In 542, the method may include receiving a first endorsement of thestorage request from a first endorser node, the first endorsementcomprising a full-step hash verification of the proposed storagerequest. Furthermore, in 543, the method may include receiving a secondendorsement of the storage request from a second endorser node, thesecond endorsement comprising a reduced-step hash verification of thestorage request. According to various embodiments, the full-step hashverification may include a verification of the full-step hash of theproposed storage request signed by the client application and thereduced-step hash verification comprises an approximate verification ofthe reduced-step hash of the proposed storage request signed by theclient application.

In 544, the method may further include transmitting a storage proposalincluding the full-step hash endorsement and the reduced-step hashendorsement to an ordering node of the blockchain. For example, theproposed storage request may include a blockchain entry such as atransaction to be stored in a data block among a hash-linked chain ofdata blocks.

In some embodiments, a length of a data value created by thereduced-step hash of the proposed storage request is equal to a lengthof a data value created by the full-step hash of the proposed storagerequest. In some embodiments, the full-step hash may include repeatedperformance of a hash function on a data value of the proposed storagerequest a first predetermined number of times, and the reduced-step hashmay include repeated performance of the hash function on the data valueof the proposed storage request a second predetermined number of timesthat is less than the first predetermined number of times. In someembodiments, the second endorsement may be received via a message whichcomprises a message element indicating the message comprises thereduced-step hash verification.

FIG. 5J illustrates a method 540B of endorsing a transaction with areduced-step hash verification according to example embodiments. Themethod may be performed by an endorser node in a blockchain. Referringto FIG. 5J, in 546 the method may include receiving, from a clientapplication, a storage request that comprises a full-step hash of a datavalue signed by the client application and a reduced-step hash of thedata value signed by the client application. For example, the full-stephash of the data value may be generated by repeated performance of ahash function a first predetermined number of times, and thereduced-step hash of the data value may be generated by repeatedperformance of the hash function a second predetermined number of timesthat is less than the first predetermined number of times.

In 547, the method may include determining whether to verify thefull-step hash of the storage request or the reduced-step hash of thestorage request. Here, the determination may be based on a blockchainpolicy, a predetermined instruction, an element in the message,randomly, or the like. In response to a determination to verify thereduced-step hash of the storage request, in 548 the method may includegenerating an approximate hash verification for the reduced-step hash ofthe data value, and in 549, the method may include transmitting anendorsement response to the client application which includes thegenerated approximate hash verification.

In some embodiments, the transmitting may further include transmittingan indicator within the endorsement response indicating the approximatehash verification has been performed. In some embodiments, the storagerequest may include a blockchain entry for storage within a data blockamong a hash-linked chain of data blocks. In some embodiments, themethod may further include executing the proposed storage request andgenerating a hash of the proposed storage request with a reduced-stephash.

FIG. 5K illustrates a method 550A of performing an approximate hashverification on a data block according to example embodiments. Forexample, the method may be performed by a blockchain peer node thatmanages and stores a replica of a distribute ledger including theblockchain. Referring to FIG. 5K, in 551, the method may includereceiving a data block for storage on a blockchain from an orderer node,where the data block may include a full-step hash of a storage requestand a reduced-step hash of the storage request. Here, the full-step hashof the storage request may be generated by application of a hashfunction a first predetermined number of times and the reduced-step hashof the storage request may be generated by application of the hashfunction a second predetermined number of times that is less than thefirst predetermined number of times.

In 552, the method may include performing an approximate hashverification on the data block based on the reduced-step hash of thestorage request included in the data block. Further, in 553, the methodmay include, in response to a success of the approximate hashverification, committing the data block among a hash-linked chain ofdata blocks stored within a distributed ledger of a blockchain. In thisexample, the storage request may be a transaction that is stored withina Merkle tree data structure of the data block.

In some embodiments, the method may further include determining whetherto perform a full-step hash verification or the approximate hashverification based on a random protocol. In some embodiments, theapproximate hash verification may include generating the reduced-stephash of the storage request for verification without generating thefull-step hash of the storage request. In some embodiments, the methodmay further include, in response to a failure of the approximate hashverification, committing the data block to the hash-linked chain of datablocks stored within a distributed ledger of a blockchain with anindicator that the storage request failed. In some embodiments, thecommitting may include storing the approximate hash verification in thedata block of the hash-linked chain of blocks and storing a fileincluded in the storage proposal within an off-chain storage.

FIG. 5L illustrates a method 550B of ordering reduced-step hashes oftransactions in a data block according to example embodiments. Forexample, the method may be performed by an ordering node on ablockchain. Referring to FIG. 5L, in 556, the method may includereceiving reduced-step hashes and full-step hashes of a plurality ofstorage requests from a plurality of client applications, respectively.In 557, the method may include arranging the reduced-step hashes withina data block based on timing information such as a timestamp, etc.included in the storage requests. Here, the storage requests may includedifferent transactions from different parties on the blockchain.

In 558, the method may include transmitting the data block with theordered reduced-step hashes to a plurality of blockchain peer nodes forinclusion within a blockchain. For example, the full-step hash of astorage request may be generated by application of a hash function afirst predetermined number of times and a reduced-step hash of thestorage request may be generated by application of the hash function asecond predetermined number of times that is less than the firstpredetermined number of times.

In some embodiments, the hash function may include a non-linear functionthat is applied to content within the storage request. In someembodiments, a length of a data value created by the full-step hash ofthe storage request is equal to a length of a data value created by thereduced-step hash of the storage request. In some embodiments, thearranging may include arranging the reduced-step hashes within the datablock in a chronological order of in which they were received. In someembodiments, the method may further include storing the full-step hasheswith the reduced-step hashes in the data block.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to performvarious operations according to example embodiments. Referring to FIG.6B, the system 640 includes a module 612 and a module 614. The module614 includes a blockchain 620 and a smart contract 630 (which may resideon the blockchain 620), that may execute any of the operational steps608 (in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smartcontract configuration among contracting parties and a mediating serverconfigured to enforce the smart contract terms on the blockchainaccording to example embodiments. Referring to FIG. 6C, theconfiguration 650 may represent a communication session, an assettransfer session or a process or procedure that is driven by a smartcontract 630 which explicitly identifies one or more user devices 652and/or 656. The execution, operations and results of the smart contractexecution may be managed by a server 654. Content of the smart contract630 may require digital signatures by one or more of the entities 652and 656 which are parties to the smart contract transaction. The resultsof the smart contract execution may be written to a blockchain 620 as ablockchain transaction. The smart contract 630 resides on the blockchain620 which may reside on one or more computers, servers, processors,memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 720, according to example embodiments, and FIG. 7Billustrates contents of a new data block structure 730 for blockchain,according to example embodiments. Referring to FIG. 7A, clients (notshown) may submit transactions to blockchain nodes 711, 712, and/or 713.Clients may be instructions received from any source to enact activityon the blockchain 720. As an example, clients may be applications thatact on behalf of a requester, such as a device, person or entity topropose transactions for the blockchain. The plurality of blockchainpeers (e.g., blockchain nodes 711, 712, and 713) may maintain a state ofthe blockchain network and a copy of the distributed ledger 720.Different types of blockchain nodes/peers may be present in theblockchain network including endorsing peers which simulate and endorsetransactions proposed by clients and committing peers which verifyendorsements, validate transactions, and commit transactions to thedistributed ledger 720. In this example, the blockchain nodes 711, 712,and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable,sequenced records in blocks, and a state database 724 (current worldstate) maintaining a current state of the blockchain 722. Onedistributed ledger 720 may exist per channel and each peer maintains itsown copy of the distributed ledger 720 for each channel of which theyare a member. The blockchain 722 is a transaction log, structured ashash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 722 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 722 represents every transaction that has come before it. Theblockchain 722 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722may be stored in the state database 724. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 722. Chaincode invocations executetransactions against the current state in the state database 724. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 724. The state database 724may include an indexed view into the transaction log of the blockchain722, it can therefore be regenerated from the chain at any time. Thestate database 724 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 712 is a committing peer thathas received a new data new data block 730 for storage on blockchain720. The first block in the blockchain may be referred to as a genesisblock which includes information about the blockchain, its members, thedata stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 720. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 724 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the newdata block 730 may be broadcast to committing peers (e.g., blockchainnodes 711, 712, and 713). In response, each committing peer validatesthe transaction within the new data block 730 by checking to make surethat the read set and the write set still match the current world statein the state database 724. Specifically, the committing peer candetermine whether the read data that existed when the endorserssimulated the transaction is identical to the current world state in thestate database 724. When the committing peer validates the transaction,the transaction is written to the blockchain 722 on the distributedledger 720, and the state database 724 is updated with the write datafrom the read-write set. If a transaction fails, that is, if thecommitting peer finds that the read-write set does not match the currentworld state in the state database 724, the transaction ordered into ablock will still be included in that block, but it will be marked asinvalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a datablock) that is stored on the blockchain 722 of the distributed ledger720 may include multiple data segments such as a block header 740, blockdata 750, and block metadata 760. It should be appreciated that thevarious depicted blocks and their contents, such as new data block 730and its contents. shown in FIG. 7B are merely examples and are not meantto limit the scope of the example embodiments. The new data block 730may store transactional information of N transaction(s) (e.g., 1, 10,100, 500, 1000, 2000, 3000, etc.) within the block data 750. The newdata block 730 may also include a link to a previous block (e.g., on theblockchain 722 in FIG. 7A) within the block header 740. In particular,the block header 740 may include a hash of a previous block's header.The block header 740 may also include a unique block number, a hash ofthe block data 750 of the new data block 730, and the like. The blocknumber of the new data block 730 may be unique and assigned in variousorders, such as an incremental/sequential order starting from zero.

The block data 750 may store transactional information of eachtransaction that is recorded within the new data block 730. For example,the transaction data may include one or more of a type of thetransaction, a version, a timestamp, a channel ID of the distributedledger 720, a transaction ID, an epoch, a payload visibility, achaincode path (deploy tx), a chaincode name, a chaincode version, input(chaincode and functions), a client (creator) identify such as a publickey and certificate, a signature of the client, identities of endorsers,endorser signatures, a proposal hash, chaincode events, response status,namespace, a read set (list of key and version read by the transaction,etc.), a write set (list of key and value, etc.), a start key, an endkey, a list of keys, a Merkel tree query summary, and the like. Thetransaction data may be stored for each of the N transactions.

In some embodiments, the block data 750 may also store approximate hashverification data 762 which may include a reduced-step hash, a full-stephash, an approximate verification, a full verification, and the like,within a data block among a hash-linked chain of blocks in theblockchain 722. The approximate hash verification data 762 may begenerated based on one or more of the steps, features, processes and/oractions described or depicted herein. Accordingly, the approximate hashverification data 762 can be stored in an immutable log of blocks on thedistributed ledger 720. Some of the benefits of storing the approximatehash verification data 762 include conserving computational resourceswhen verifying a hash value stored and/or transmitted in associationwith the blockchain 720. Although in FIG. 7B the blockchain verificationdata 762 is depicted in the block data 750 but could also be located inthe block header 740 or the block metadata 760.

The block metadata 760 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 712) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsin the block data 750 and a validation code identifying whether atransaction was valid/invalid.

FIG. 7C illustrates an embodiment of a blockchain 770 for digitalcontent in accordance with the embodiments described herein. The digitalcontent may include one or more files and associated information. Thefiles may include media, images, video, audio, text, links, graphics,animations, web pages, documents, or other forms of digital content. Theimmutable, append-only aspects of the blockchain serve as a safeguard toprotect the integrity, validity, and authenticity of the digitalcontent, making it suitable use in legal proceedings where admissibilityrules apply or other settings where evidence is taken in toconsideration or where the presentation and use of digital informationis otherwise of interest. In this case, the digital content may bereferred to as digital evidence.

The blockchain may be formed in various ways. In one embodiment, thedigital content may be included in and accessed from the blockchainitself. For example, each block of the blockchain may store a hash valueof reference information (e.g., header, value, etc.) along theassociated digital content. The hash value and associated digitalcontent may then be encrypted together. Thus, the digital content ofeach block may be accessed by decrypting each block in the blockchain,and the hash value of each block may be used as a basis to reference aprevious block. This may be illustrated as follows:

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value NDigital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in theblockchain. For example, the blockchain may store the encrypted hashesof the content of each block without any of the digital content. Thedigital content may be stored in another storage area or memory addressin association with the hash value of the original file. The otherstorage area may be the same storage device used to store the blockchainor may be a different storage area or even a separate relationaldatabase. The digital content of each block may be referenced oraccessed by obtaining or querying the hash value of a block of interestand then looking up that has value in the storage area, which is storedin correspondence with the actual digital content. This operation may beperformed, for example, a database gatekeeper. This may be illustratedas follows:

Blockchain Storage Area Block 1 Hash Value Block 1 Hash Value . . .Content . . . . . . Block N Hash Value Block N Hash Value . . . Content

In the example embodiment of FIG. 7C, the blockchain 770 includes anumber of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linkedin an ordered sequence, where N≥1. The encryption used to link theblocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed orunkeyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . .. 778 _(N) are subject to a hash function which produces n-bitalphanumeric outputs (where n is 256 or another number) from inputs thatare based on information in the blocks. Examples of such a hash functioninclude, but are not limited to, a SHA-type (SHA stands for Secured HashAlgorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm,Merkle-tree algorithm, nonce-based algorithm, and anon-collision-resistant PRF algorithm. In another embodiment, the blocks778 ₁, 778 ₂, . . . , 778 _(N) may be cryptographically linked by afunction that is different from a hash function. For purposes ofillustration, the following description is made with reference to a hashfunction, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . , 778 _(N) in the blockchainincludes a header, a version of the file, and a value. The header andthe value are different for each block as a result of hashing in theblockchain. In one embodiment, the value may be included in the header.As described in greater detail below, the version of the file may be theoriginal file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesisblock and includes the header 772 ₁, original file 774 ₁, and an initialvalue 776 ₁. The hashing scheme used for the genesis block, and indeedin all subsequent blocks, may vary. For example, all the information inthe first block 778 ₁ may be hashed together and at one time, or each ora portion of the information in the first block 778 ₁ may be separatelyhashed and then a hash of the separately hashed portions may beperformed.

The header 772 ₁ may include one or more initial parameters, which, forexample, may include a version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, duration, mediaformat, source, descriptive keywords, and/or other informationassociated with original file 774 ₁ and/or the blockchain. The header772 ₁ may be generated automatically (e.g., by blockchain networkmanaging software) or manually by a blockchain participant. Unlike theheader in other blocks 778 ₂ to 778 _(N) in the blockchain, the header772 ₁ in the genesis block does not reference a previous block, simplybecause there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, dataas captured by a device with or without processing prior to itsinclusion in the blockchain. The original file 774 ₁ is received throughthe interface of the system from the device, media source, or node. Theoriginal file 774 ₁ is associated with metadata, which, for example, maybe generated by a user, the device, and/or the system processor, eithermanually or automatically. The metadata may be included in the firstblock 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated basedon one or more unique attributes of the original file 774 ₁. In oneembodiment, the one or more unique attributes may include the hash valuefor the original file 774 ₁, metadata for the original file 774 ₁, andother information associated with the file. In one implementation, theinitial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file    -   2) originating device ID    -   3) starting timestamp for the original file    -   4) initial storage location of the original file    -   5) blockchain network member ID for software to currently        control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers,files, and values. However, unlike the first block 772 ₁, each of theheaders 772 ₂ to 772 _(N) in the other blocks includes the hash value ofan immediately preceding block. The hash value of the immediatelypreceding block may be just the hash of the header of the previous blockor may be the hash value of the entire previous block. By including thehash value of a preceding block in each of the remaining blocks, a tracecan be performed from the Nth block back to the genesis block (and theassociated original file) on a block-by-block basis, as indicated byarrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may alsoinclude other information, e.g., version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, and/or otherparameters or information associated with the corresponding files and/orthe blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to theoriginal file or may be a modified version of the original file in thegenesis block depending, for example, on the type of processingperformed. The type of processing performed may vary from block toblock. The processing may involve, for example, any modification of afile in a preceding block, such as redacting information or otherwisechanging the content of, taking information away from, or adding orappending information to the files.

Additionally, or alternatively, the processing may involve merelycopying the file from a preceding block, changing a storage location ofthe file, analyzing the file from one or more preceding blocks, movingthe file from one storage or memory location to another, or performingaction relative to the file of the blockchain and/or its associatedmetadata. Processing which involves analyzing a file may include, forexample, appending, including, or otherwise associating variousanalytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the otherblocks are unique values and are all different as a result of theprocessing performed. For example, the value in any one blockcorresponds to an updated version of the value in the previous block.The update is reflected in the hash of the block to which the value isassigned. The values of the blocks therefore provide an indication ofwhat processing was performed in the blocks and also permit a tracingthrough the blockchain back to the original file. This tracking confirmsthe chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previousblock are redacted, blocked out, or pixelated in order to protect theidentity of a person shown in the file. In this case, the blockincluding the redacted file will include metadata associated with theredacted file, e.g., how the redaction was performed, who performed theredaction, timestamps where the redaction(s) occurred, etc. The metadatamay be hashed to form the value. Because the metadata for the block isdifferent from the information that was hashed to form the value in theprevious block, the values are different from one another and may berecovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., anew hash value computed) to form the value of a current block when anyone or more of the following occurs. The new hash value may be computedby hashing all or a portion of the information noted below, in thisexample embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed        in any way (e.g., if the file was redacted, copied, altered,        accessed, or some other action was taken)    -   b) new storage location for the file    -   c) new metadata identified associated with the file    -   d) transfer of access or control of the file from one blockchain        participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent thestructure of the blocks in the blockchain 790 in accordance with oneembodiment. The block, Block_(i), includes a header 772 _(i), a file 774_(i), and a value 776 _(i).

The header 772 ₁ includes a hash value of a previous block Block_(i-1)and additional reference information, which, for example, may be any ofthe types of information (e.g., header information including references,characteristics, parameters, etc.) discussed herein. All blocksreference the hash of a previous block except, of course, the genesisblock. The hash value of the previous block may be just a hash of theheader in the previous block or a hash of all or a portion of theinformation in the previous block, including the file and metadata.

The file 774 ₁ includes a plurality of data, such as Data 1, Data 2, . .. , Data N in sequence. The data are tagged with metadata Metadata 1,Metadata 2, . . . , Metadata N which describe the content and/orcharacteristics associated with the data. For example, the metadata foreach data may include information to indicate a timestamp for the data,process the data, keywords indicating the persons or other contentdepicted in the data, and/or other features that may be helpful toestablish the validity and content of the file as a whole, andparticularly its use a digital evidence, for example, as described inconnection with an embodiment discussed below. In addition to themetadata, each data may be tagged with reference REF₁, REF₂, . . . ,REF_(N) to a previous data to prevent tampering, gaps in the file, andsequential reference through the file.

Once the metadata is assigned to the data (e.g., through a smartcontract), the metadata cannot be altered without the hash changing,which can easily be identified for invalidation. The metadata, thus,creates a data log of information that may be accessed for use byparticipants in the blockchain.

The value 776 _(i) is a hash value or other value computed based on anyof the types of information previously discussed. For example, for anygiven block Block_(i), the value for that block may be updated toreflect the processing that was performed for that block, e.g., new hashvalue, new storage location, new metadata for the associated file,transfer of control or access, identifier, or other action orinformation to be added. Although the value in each block is shown to beseparate from the metadata for the data of the file and header, thevalue may be based, in part or whole, on this metadata in anotherembodiment.

Once the blockchain 770 is formed, at any point in time, the immutablechain-of-custody for the file may be obtained by querying the blockchainfor the transaction history of the values across the blocks. This query,or tracking procedure, may begin with decrypting the value of the blockthat is most currently included (e.g., the last (N^(th)) block), andthen continuing to decrypt the value of the other blocks until thegenesis block is reached and the original file is recovered. Thedecryption may involve decrypting the headers and files and associatedmetadata at each block, as well.

Decryption is performed based on the type of encryption that took placein each block. This may involve the use of private keys, public keys, ora public key-private key pair. For example, when asymmetric encryptionis used, blockchain participants or a processor in the network maygenerate a public key and private key pair using a predeterminedalgorithm. The public key and private key are associated with each otherthrough some mathematical relationship. The public key may bedistributed publicly to serve as an address to receive messages fromother users, e.g., an IP address or home address. The private key iskept secret and used to digitally sign messages sent to other blockchainparticipants. The signature is included in the message so that therecipient can verify using the public key of the sender. This way, therecipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on theblockchain, but without having to actually register anywhere. Also,every transaction that is executed on the blockchain is digitally signedby the sender using their private key. This signature ensures that onlythe owner of the account can track and process (if within the scope ofpermission determined by a smart contract) the file of the blockchain.

FIGS. 8A and 8B illustrate additional examples of use cases forblockchain which may be incorporated and used herein. In particular,FIG. 8A illustrates an example 800 of a blockchain 810 which storesmachine learning (artificial intelligence) data. Machine learning relieson vast quantities of historical data (or training data) to buildpredictive models for accurate prediction on new data. Machine learningsoftware (e.g., neural networks, etc.) can often sift through millionsof records to unearth non-intuitive patterns.

In the example of FIG. 8A, a host platform 820 builds and deploys amachine learning model for predictive monitoring of assets 830. Here,the host platform 820 may be a cloud platform, an industrial server, aweb server, a personal computer, a user device, and the like. Assets 830can be any type of asset (e.g., machine or equipment, etc.) such as anaircraft, locomotive, turbine, medical machinery and equipment, oil andgas equipment, boats, ships, vehicles, and the like. As another example,assets 830 may be non-tangible assets such as stocks, currency, digitalcoins, insurance, or the like.

The blockchain 810 can be used to significantly improve both a trainingprocess 802 of the machine learning model and a predictive process 804based on a trained machine learning model. For example, in 802, ratherthan requiring a data scientist/engineer or other user to collect thedata, historical data may be stored by the assets 830 themselves (orthrough an intermediary, not shown) on the blockchain 810. This cansignificantly reduce the collection time needed by the host platform 820when performing predictive model training. For example, using smartcontracts, data can be directly and reliably transferred straight fromits place of origin to the blockchain 810. By using the blockchain 810to ensure the security and ownership of the collected data, smartcontracts may directly send the data from the assets to the individualsthat use the data for building a machine learning model. This allows forsharing of data among the assets 830.

The collected data may be stored in the blockchain 810 based on aconsensus mechanism. The consensus mechanism pulls in (permissionednodes) to ensure that the data being recorded is verified and accurate.The data recorded is time-stamped, cryptographically signed, andimmutable. It is therefore auditable, transparent, and secure. AddingIoT devices which write directly to the blockchain can, in certain cases(i.e. supply chain, healthcare, logistics, etc.), increase both thefrequency and accuracy of the data being recorded.

Furthermore, training of the machine learning model on the collecteddata may take rounds of refinement and testing by the host platform 820.Each round may be based on additional data or data that was notpreviously considered to help expand the knowledge of the machinelearning model. In 802, the different training and testing steps (andthe data associated therewith) may be stored on the blockchain 810 bythe host platform 820. Each refinement of the machine learning model(e.g., changes in variables, weights, etc.) may be stored on theblockchain 810. This provides verifiable proof of how the model wastrained and what data was used to train the model. Furthermore, when thehost platform 820 has achieved a finally trained model, the resultingmodel may be stored on the blockchain 810.

After the model has been trained, it may be deployed to a liveenvironment where it can make predictions/decisions based on theexecution of the final trained machine learning model. For example, in804, the machine learning model may be used for condition-basedmaintenance (CBM) for an asset such as an aircraft, a wind turbine, ahealthcare machine, and the like. In this example, data fed back fromthe asset 830 may be input the machine learning model and used to makeevent predictions such as failure events, error codes, and the like.Determinations made by the execution of the machine learning model atthe host platform 820 may be stored on the blockchain 810 to provideauditable/verifiable proof. As one non-limiting example, the machinelearning model may predict a future breakdown/failure to a part of theasset 830 and create alert or a notification to replace the part. Thedata behind this decision may be stored by the host platform 820 on theblockchain 810. In one embodiment the features and/or the actionsdescribed and/or depicted herein can occur on or with respect to theblockchain 810.

New transactions for a blockchain can be gathered together into a newblock and added to an existing hash value. This is then encrypted tocreate a new hash for the new block. This is added to the next list oftransactions when they are encrypted, and so on. The result is a chainof blocks that each contain the hash values of all preceding blocks.Computers that store these blocks regularly compare their hash values toensure that they are all in agreement. Any computer that does not agree,discards the records that are causing the problem. This approach is goodfor ensuring tamper-resistance of the blockchain, but it is not perfect.

One way to game this system is for a dishonest user to change the listof transactions in their favor, but in a way that leaves the hashunchanged. This can be done by brute force, in other words by changing arecord, encrypting the result, and seeing whether the hash value is thesame. And if not, trying again and again and again until it finds a hashthat matches. The security of blockchains is based on the belief thatordinary computers can only perform this kind of brute force attack overtime scales that are entirely impractical, such as the age of theuniverse. By contrast, quantum computers are much faster (1000s of timesfaster) and consequently pose a much greater threat.

FIG. 8B illustrates an example 850 of a quantum-secure blockchain 852which implements quantum key distribution (QKD) to protect against aquantum computing attack. In this example, blockchain users can verifyeach other's identities using QKD. This sends information using quantumparticles such as photons, which cannot be copied by an eavesdropperwithout destroying them. In this way, a sender and a receiver throughthe blockchain can be sure of each other's identity.

In the example of FIG. 8B, four users are present 854, 856, 858, and860. Each of pair of users may share a secret key 862 (i.e., a QKD)between themselves. Since there are four nodes in this example, sixpairs of nodes exists, and therefore six different secret keys 862 areused including QKD_(AB), QKD_(AC), QKD_(AD), QKD_(BC), QKD_(BD), andQKD_(CD). Each pair can create a QKD by sending information usingquantum particles such as photons, which cannot be copied by aneavesdropper without destroying them. In this way, a pair of users canbe sure of each other's identity.

The operation of the blockchain 852 is based on two procedures (i)creation of transactions, and (ii) construction of blocks that aggregatethe new transactions. New transactions may be created similar to atraditional blockchain network. Each transaction may contain informationabout a sender, a receiver, a time of creation, an amount (or value) tobe transferred, a list of reference transactions that justifies thesender has funds for the operation, and the like. This transactionrecord is then sent to all other nodes where it is entered into a poolof unconfirmed transactions. Here, two parties (i.e., a pair of usersfrom among 854-860) authenticate the transaction by providing theirshared secret key 862 (QKD). This quantum signature can be attached toevery transaction making it exceedingly difficult to tamper with. Eachnode checks their entries with respect to a local copy of the blockchain852 to verify that each transaction has sufficient funds. However, thetransactions are not yet confirmed.

Rather than perform a traditional mining process on the blocks, theblocks may be created in a decentralized manner using a broadcastprotocol. At a predetermined period of time (e.g., seconds, minutes,hours, etc.) the network may apply the broadcast protocol to anyunconfirmed transaction thereby to achieve a Byzantine agreement(consensus) regarding a correct version of the transaction. For example,each node may possess a private value (transaction data of thatparticular node). In a first round, nodes transmit their private valuesto each other. In subsequent rounds, nodes communicate the informationthey received in the previous round from other nodes. Here, honest nodesare able to create a complete set of transactions within a new block.This new block can be added to the blockchain 852. In one embodiment thefeatures and/or the actions described and/or depicted herein can occuron or with respect to the blockchain 852.

FIG. 9 illustrates an example system 900 that supports one or more ofthe example embodiments described and/or depicted herein. The system 900comprises a computer system/server 902, which is operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 902 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like.

Computer system/server 902 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 902 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9, computer system/server 902 in cloud computing node900 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 902 may include, but are notlimited to, one or more processors or processing units 904, a systemmemory 906, and a bus that couples various system components includingsystem memory 906 to processor 904.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 902 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 902, and it includes both volatileand non-volatile media, removable and non-removable media. System memory906, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 906 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)910 and/or cache memory 912. Computer system/server 902 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 914 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 906 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 916, having a set (at least one) of program modules 918,may be stored in memory 906 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 918 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 902 may also communicate with one or moreexternal devices 920 such as a keyboard, a pointing device, a display922, etc.; one or more devices that enable a user to interact withcomputer system/server 902; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 902 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 924. Still yet, computer system/server 902 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 926. As depicted, network adapter 926communicates with the other components of computer system/server 902 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 902. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. A computing system comprising: a networkinterface configured to receive a location of an output stored on a datastructure of a blockchain, where the location comprises a path of hashesof blockchain transactions within a block of the blockchain generated bya reduced-step hash instead of a full-step hash of the blockchain; and ahardware processor configured to perform an approximate hashverification on each node in the path of hashes based on thereduced-step hash to verify whether the output is unused, and, inresponse to a determination that the output is unused as a result of theapproximate hash verification, approve a use of the output by a clientassociated with the output; wherein each node in the path includes areduced-step hash generated based on hash values of respective childnodes in the data structure.
 2. The computing system of claim 1, whereinthe full-step hash comprises repeated performance of a function a firstpredetermined number of times, and the reduced-step hash comprisesrepeated performance of the function a second predetermined number oftimes that is less than the first predetermined number of times.
 3. Thecomputing system of claim 1, wherein the path of hashes, when hashedtogether, produce an identifier of a data block in the blockchain whichstores the unused output.
 4. The computing system of claim 3, whereinthe approximate hash verification further comprises verification ofwhether the generated result is the identifier of the data block.
 5. Thecomputing system of claim 1, wherein the path of hashes comprises a pathof hashes on a Merkle tree from a leaf node that corresponds to ablockchain transaction to a root node of the Merkle tree.
 6. Thecomputing system of claim 1, wherein the hardware processor is furtherconfigured to prevent the use of the output, in response to adetermination that the output is used as a result of the approximatehash verification.
 7. A method comprising: receiving a location of anoutput stored on a data structure of a blockchain, where the locationcomprises a path of hashes of blockchain transactions within a block ofthe blockchain generated by a reduced-step hash instead of a full-stephash of the blockchain; performing an approximate hash verification oneach node in the path of hashes based on the reduced-step hash to verifywhether the output is unused; and in response to a determination thatthe output is unused as a result of the approximate hash verification,approving a use of the output by a client associated with the output;wherein each node in the path includes a reduced-step hash generatedbased on hash values of respective child nodes in the data structure. 8.The method of claim 7, wherein the full-step hash comprises repeatedperformance of a function a first predetermined number of times, and thereduced-step hash comprises repeated performance of the function asecond predetermined number of times that is less than the firstpredetermined number of times.
 9. The method of claim 7, wherein thepath of hashes, when hashed together, produce an identifier of a datablock in the blockchain storing the unused output.
 10. The method ofclaim 9, wherein the approximate hash verification further comprisesverifying whether the generated result is the identifier of the datablock.
 11. The method of claim 7, wherein the path of hashes comprises apath of hashes on a Merkle tree from a leaf node corresponding to ablockchain transaction to a root node of the Merkle tree.
 12. The methodof claim 7, further comprising preventing the use of the output, inresponse to determining that the output is used as a result of theapproximate hash verification.
 13. A non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform a method comprising: receiving a location of anoutput stored on a data structure of a blockchain, where the locationcomprises a path of hashes of blockchain transactions within a block ofthe blockchain generated by a reduced-step hash instead of a full-stephash of the blockchain; performing an approximate hash verification oneach node in the path of hashes based on the reduced-step hash to verifywhether the output is unused; and in response to a determination thatthe output is unused as a result of the approximate hash verification,approving a use of the output by a client associated with the output;wherein each node in the path includes a reduced-step hash generatedbased on hash values of respective child nodes in the data structure.14. A computing system comprising: a network interface configured toreceive a hashed identifier of an output stored on a data structure of ablockchain, where the hashed identifier is generated by a reduced-hashof the blockchain performed on a sequence of blockchain data valuesinstead of a full-hash of the blockchain; and a hardware processorconfigured to perform an approximate hash verification on eachblockchain data value in the sequence based on the reduced-hash toverify whether the output is unused, and in response to a determinationthat the output is unused as a result of the approximate hashverification, approve a use of the output by a client associated withthe output; wherein the blockchain includes a path of hashes ofblockchain transactions; wherein each node in the path includes areduced-step hash generated based on hash values of respective childnodes in the data structure.
 15. The computing system of claim 14,wherein the hashed identifier comprises an identification of a datablock in the blockchain that stores the unused output.
 16. The computingsystem of claim 14, wherein the hashed identifier is generated by theprocessor through a chain of reduced-hashes based on a path of theoutput stored in a blockchain data structure.
 17. The computing systemof claim 14, wherein the hardware processor is further configured to, inresponse to a determination that the output is used as a result of theapproximate hash verification, prevent the use of the output.
 18. Thecomputing system of claim 14, wherein the hardware processor is furtherconfigured to store hashed identifiers of a plurality of data blocks andidentifiers of the outputs stored in each data block.
 19. A methodcomprising: receiving a hashed identifier of an output stored on a datastructure of a blockchain, where the hashed identifier is generated by areduced-step hash of the blockchain performed on a sequence ofblockchain data values instead of a full-step hash of the blockchain;performing an approximate hash verification on each blockchain datavalue in the sequence based on the reduced-step hash to verify whetherthe output is unused; and in response to a determination that the outputis unused as a result of the approximate hash verification, approving ause of the output by a client associated with the output; wherein theblockchain includes a path of hashes of blockchain transactions; whereineach node in the path includes a reduced-step hash generated based onhash values of respective child nodes in the data structure.
 20. Themethod of claim 19, wherein the hashed identifier comprises anidentification of a data block in the blockchain storing the unusedoutput.
 21. The method of claim 19, wherein the hashed identifier isgenerated by performing a chain of reduced-step hashes based on a pathof the output stored in a blockchain data structure.
 22. The method ofclaim 19, further comprising, in response to determining that the outputis used as a result of the approximate hash verification, preventing theuse of the output.
 23. The method of claim 19, further comprisingstoring hashed identifiers of a plurality of data blocks and identifiersof the outputs stored in each data block.